.header {
    background-color: #f2f2f2;
    padding: 20px;
    text-align: center;
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

li a:hover:not(.active) {
    background-color: #111;
}

.active {
    background-color: #4CAF50;
}

form {
    width: 50%;
    margin: 0 auto;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

label {
    display: block;
    margin-bottom: 8px;
}

input[type="text"], input[type="email"], select {
    width: 100%;
    padding: 6px 10px;
    margin: 8px 0;
    box-sizing: border-box;
    border: 1px solid #555;
    border-radius: 4px;
    font-size: 16px;
}

button[type="submit"] {
    padding: 10px;
    background-color: #4CAF50;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

button[type="submit"]:hover {
    background-color: #3e8e41;
}

table {
    border-collapse: collapse;
    width: 100%;
}

th, td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: left;
}

th {
    background-color: #f2f2f2;
}

tr:nth-child(even) {
    background-color: #f2f2f2;
}

.header {
    background-color: #f2f2f2;
    padding: 20px;
    text-align: center;
}

a {
    text-decoration: none;
    color: #333;
}

.add-button {
    margin-bottom: 20px;
    padding: 10px;
    background-color: #4CAF50;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

.add-button:hover {
    background-color: #3e8e41;
}